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[IEEE 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Waikoloa Village, HI (2018.6.10-2018.6.15)] 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Correlative Microscopy Characterization of Cesium-Lead-Bromide Thin-films
摘要： Inorganic cesium lead halide compounds have gained an increasing interest in the perovskite photovoltaics research community. These compounds are mixed into state of the art organic lead halide perovskite solar cells to provide for more thermal stability, and CsPbX3 (x=I, Br, Cl) nanocubes are investigated as standalone emitter material in light emitting diodes. Eventually, reproducible, single-phase CsPbBr3 thin films could also provide us with a more stable inorganic material for perovskite solar cells. In the present work, we report on microscopic structural and optoelectronic properties of Cs-Pb-Br thin films prepared by different synthesis methods and studied using various electron-microscopy techniques.
关键词： cesium lead bromide,secondary phases,phase distribution,correlative microscopy,electron microscopy,halide Perovskites
更新于2025-11-21 10:59:37
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Cesium lead halide perovskite nanocrystals for ultraviolet and blue light blocking
摘要： Direct exposure to ultraviolet (UV) light is closely related to various harmful effects [1-3], ranging from skin injures to cancer originated from DNA damage. Recent years, some studies reported that blue light are also detrimental to humans [4,5], for example, the blue light could cause photochemical lesions to human retinal within the intensity range of the natural light [6]. Furthermore, blue light is responsible for the solar retinitis and may play a role in age-related macular degeneration. Importantly, the harmful effects of blue lights generated from the electronic display devices should also be careful [7]. Thus, the development of new UV and blue light shielding materials has been received much attention [8]. In the past few years, there has been an increased awareness of the importance to develop UV shielding materials. A variety of materials have been used to prevent UV lesions. Organic molecules like avobenzone or oxybenzone have been used as a UV absorber for many years, but the self-degradation limits their usage time. Inorganic materials such as zinc oxide (ZnO) and titanium oxide (TiO2) have been used intensively for UV shielding [9-12]. However, photocatalytic properties and self-degradations of the ZnO and TiO2 based absorbers also hindered their applications [13,14]. Other materials, e.g., graphene oxide-poly(vinyl alcohol) composite film and lanthanide complex functionalized cellulose nanopaper were also reported for UV shielding [15,16]. Whereas, the excellent UV-filtering capability of these films was obtained by sacrificing the visible light transmittance. Therefore, fabricating UV and blue light blocking materials with good photostability and high transparency to the rest of visible light still remains a challenge and is urgently needed to be developed. Recently, because of the outstanding performance in photovoltaic applications, lead halide perovskite APbX3 (where A = CH3NH3+, (NH2)2CH+ and Cs+, X = Cl?, Br? and I?) has become the most noticeable materials [17-22]. These perovskite nanocrystals exhibit intriguing features [23], such as easy tunable band gap, sharp optical absorption edges and high quantum efficiency with narrow emission spectra. These nanocrystals have been studied extensively for various optical applications, especially light emitting diodes and lasers [24-27]. Post modification of perovskite nanocrystals by anion exchange enables the absorbance band gap tuned from ultraviolet to near infrared spectra [28,29]. In addition, the perovskite nanocrystals show large absorption range, which offers the great potential for UV and blue light shielding applications. Although the tunable absorption-band edge of perovskite nanocrystals has already been realized, there have not been reports on developing UV and blue light blocking material with tunable absorption-band edge. Herein, we aim to the development of a simple and easy way to fabricate UV and blue light blocking material by mixing pervoskite nanocrystals and ethyl cellulose (EC). In this study, EC was used as a host material for the CsPb(Cl/Br)3 pervoskite nanocrystals. By tuning the ratio of Br to Cl, the blocked wavelength range could be easily controlled. Using the sharp absorption edges, the material possesses excellent light blocking ability in the range of 200-460 nm and maintains high transparency (95%) to visible light in the range beyond blue light.
关键词： UV blocking,Cesium lead halide nanocrystals,Blue light blocking,Tunable adsorption edge,Perovskite nanocrystals
更新于2025-09-23 15:23:52
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Polymer-assisted In-situ Growth of All-Inorganic Perovskite Nanocrystal Film for Efficient and Stable Pure Red Light-emitting Devices
摘要： In the past few years, a substantial progress has been made for perovskite light-emitting devices. Both pure green and infrared thin film perovskite light-emitting devices with external quantum efficiency over 20% have been successfully achieved. However, pure red and blue thin film perovskite light-emitting diodes still suffer from inferior efficiency. Therefore, the development of efficient and stable thin film perovskite light-emitting diodes with pure red and blue emissions is urgently needed for possible applications as a new display technology and solid-state lighting. Here, we demonstrate an efficient light-emitting diode with pure red emission based on polymer-assisted in-situ growth of high quality all-inorganic CsPbBr0.6I2.4 perovskite nanocrystal film with homogenous distribution of nanocrystals in size of 20 ~ 30 nm. With this method, we can dramatically reduce the formation temperature of CsPbBr0.6I2.4 and stabilize its perovskite phase. Eventually, we successfully demonstrate a pure-red-emission perovskite light-emitting diode with a high external quantum efficiency of 6.55% and luminance of 338 cd/m2. Furthermore, the device obtains an ultra-low turn-on voltage of 1.5 V and a half-lifetime of over 0.5 hours at a high initial luminance of 300 cd/m2.
关键词： cesium-based perovskite,perovskite-polymer hybrid,Low-temperature process,pure red-emitting,perovskite LED
更新于2025-09-23 15:21:21
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Ultrafast Interfacial Charge Transfer of Cesium Lead Halide Perovskite Films CsPbX3 (X = Cl, Br, I) with Different Halogen Mixing
摘要： Understanding the interfacial charge transfer of the photoinduced transients of all-inorganic cesium lead halide perovskites (CsPbX3; X = Cl, Br, I) is critical for their photovoltaic applications. Ultrafast dynamics can provide comprehensive information about the transient behavior of the carriers and their transfer mechanism in the materials. In this work, the interfacial charge transfer of CsPbX3 films assembled with TiO2 with different halogen doping ratios was studied using femtosecond transient absorption (TA) spectroscopy combined with global analysis. Four subsequent decay processes after photoexcitation were obtained, including hot carrier cooling, free exciton forming, electron transfer, and charge recombination. The results indicate that the time constant of the interfacial electron transfer varies with the location of the trap state of these perovskites and the relative energy of CBs in the perovskite and TiO2 and that the time constant of the charge recombination can be attributed to the electron–hole interactions. These interpretations are supported by calculations based on first-principles density functional theory (DFT). Greater iodine doping in such perovskite CsPbX3/TiO2 systems increases the time constants of the electron transfer and charge recombination, which suggests that all-inorganic perovskite CsPbX3 with a high iodine content is favorable for improving the power conversion efficiency of solar cells.
关键词： cesium lead halide perovskite,transient absorption,global analysis,interfacial charge transfer
更新于2025-09-23 15:21:01
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One-step Co-evaporation of All-Inorganic Perovskite Thin Films with Room Temperature Ultralow Amplified Spontaneous Emission Threshold and Air-stability
摘要： Inorganic cesium lead halide perovskite has been successfully applied in optoelectronic field due to its remarkable optical gain properties. Unfortunately, conventional solution-processed CsPbX3 films suffer unavoidable pinhole defects and poor surface morphology, severely limiting their performance on amplified spontaneous emission (ASE) and lasing application. Herein, a dual-source thermal evaporation approach is explored in our work to achieve a uniform and high-coverage CsPbX3 polycrystalline thin film. It is found that the one-step co-evaporated CsPbBr3 (OC-CsPbBr3) thin films without post-annealing exhibit an ultralow ASE threshold of ~ 3.3 μJ/cm2 and gain coefficient above 300 cm-1. The coexistence of cubic and orthorhombic phases in this materials naturally form an energy cascade for the exciton transfer process, which enables rapid accumulation of excitons. Stable ASE intensity without degradation for at least 7 hours is also realized from OC-CsPbBr3 thin films under continuous excitation, which is superior to that in the solution-processed CsPbBr3 thin film. Notably, a Fabry-Perot (F-P) cavity laser based on the OC-CsPbBr3 thin film is first achieved, featuring an ultralow lasing threshold (1.7 μJ/cm2) and directional output (beam divergence of ~ 3.8°). This work highlights the noteworthy optical properties of OC-CsPbBr3 thin films, leading to potential available applications in the integrated optoelectronic chips.
关键词： amplified spontaneous emission,Cesium lead halide perovskite,vapor deposition,long-term stability,thin films
更新于2025-09-23 15:21:01
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INFLUENCIA DE LAS COLISIONES ATóMICAS EN LAS RESONANCIAS SUB-DOPPLER DE LA ESPECTROSCOPIA DE REFLEXIóN SELECTIVA EN LA LíNEA D2 DEL CESIO
摘要： We report a study of the re?ectivity of a glass-cesium vapor interface near the cesium D2 resonance line for cesium vapor densities from 0.9 × 1014 up to 3.2 × 1014 atoms/cm3. The experimental results are compared with calculations based on a theory on which are taken into account ?rst only the atom–atom collisions and then also taking into account the atom–wall collisions. We also detect a shift for the blue of the frequency of the peak of the resonance 4 → 5 that approximately depends linearly on the density N.
关键词： Cesium,Spectroscopy,Selective re?ection,Atomic physics
更新于2025-09-23 15:21:01
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Evolution of Morphology, Phase Composition and Photoluminescence of Cesium Lead Bromine Nanocrystals with Temperature and Precursors
摘要： Compared with CsPbBr3 nanocrystals (NCs), the study of the structure and physical properties of Cs4PbBr6 and CsPb2Br5 NCs is not sufficient. In this paper, CsPbBr3, CsPb2Br5, and Cs4PbBr6 NCs were prepared by a hot-injection method using oleylamine (OAm) and oleic acid (OA) without adding other ligands. The evolution of phase composition, morphology and photoluminescence (PL) property were investigated. It is found that rhombohedral Cs4PbBr6 was created at low temperature with low Pb/Cs ratios and short reaction time. CsPbBr3 phase was then obtained with increasing Pb/Cs ratios at high temperature through the reaction of Cs4PbBr6 and PbBr2. The evolution of phase composition occurred with time to create CsPbBr3, CsPb2Br5, and Cs4PbBr6 NCs. For a Pb/Cs molar ratio of 3, CsPbBr3 were firstly obtained at 180 °C. However, resulting sample is CsPb2Br5 phase after 120 min. The excesses PbBr2 is a key for such phase change because no similar phenomenon was observed in the case of molar ratio of Pb/Cs of 2. At low temperature (e.g. 140 and 160 °C), rhombohedral Cs4PbBr6 phase was obtained and then reacted with PbBr2 to fabricate cubic CsPbBr3 nanosheets with sizes of several hundred nanometers. With changing phase composition, cubic, rod, rhombohedral morphologies were created. The PL properties of the NCs depended strongly on the phase composition. As a result, CsPbBr3 NCs reveal highly bright PL with narrow and symmetrical PL spectra (PL peak at 520 nm). In contrast, No PL was observed for Cs4PbBr6 and CsPb2Br5 phases. The results provide a possibility to well control the growth for the application of cesium lead halide NCs.
关键词： Cesium lead bromine nanocrystals,Photoluminescence,Morphology,Phase evolution,Hot-injection method
更新于2025-09-23 15:21:01
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Boosting the efficiency and stability of perovskite solar cells through facile molecular engineering approaches
摘要： Not only the poor interaction but also trap states at interfaces and grain boundaries are suspected to be responsible for carrier losses in perovskite solar cell (PSC) architecture, leading to inferior photovoltaic performance and long-term stability. Here, facile and effective molecular engineering approaches have been reported by employing a CsF-doped SnO2 electron-transporting layer (ETL) and inserting zwitterion molecules as building blocks between perovskite and hole-transporting layer (HTL). The modification of SnO2 by alkali metal fluoride significantly improved the opto-electronic properties, indicating rapid extraction of photogenerated electrons and better light-harvesting. On the other hand, zwitterion interlayer demonstrated a considerable passivation in multiple defect states at grain boundaries of perovskite film. This strategy yielded an open-circuit voltage (VOC) of 1.23 V for triple-cation perovskite composition with the loss in potential of only 0.37 V. As a result, a considerable efficiency of 21.7% was achieved with negligible hysteresis. More importantly, such engineering approaches exhibited an admissible long-term stability under continuous light soaking at the maximum power point (MPP) tracking by retaining 90% of initial efficiency after ~800 h. In short, these initiatives have simultaneously improved the photovoltaic performance and long-term stability of PSCs. This work severely highlights the utility of molecular engineering approaches in perovskite devices and provides the basis for facilitating industrial applications in the near future.
关键词： Stability,Perovskite solar cells,Zwitterion molecules,SnO2 electron transporting layer,Cesium fluoride
更新于2025-09-23 15:19:57
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Controllable synthesis of all inorganic lead halide perovskite nanocrystals and white light-emitting diodes based on CsPbBr3 nanocrystals
摘要： The colloidal cesium lead halide perovskite nanocrystals (NCs) have attracted much attention over the past five years as a promising class of material with potential application in wide-color-gamut backlight display because of their high photoluminescence quantum yield (PLQY) and narrow-band emission (full-width at half-maximum, FWHM < 35 nm). To controllably synthesize perovskite NCs, the effects of reaction temperature and reaction time on structure, morphology, particle size and photoluminescence (PL) properties of the NCs were systematically investigated in this article. Based on these results, the formation kinetics of the perovskite NCs was analyzed and disclosed in further. Finally, a white light-emitting diode (WLED) was prepared by using synthesized CsPbBr3 NCs and K2SiF6:Mn4+ phosphors as the color converters. The WLED exhibits the bright white emission with a CIE chromaticity coordinate of (0.389, 0.376) and a wide color gamut of 123% of NTSC, indicating a potential application in the field of wide color gamut displays in the future.
关键词： Cesium lead halide perovskite,white light-emitting diodes,photoluminescent,hot-injection method,nanocrystals
更新于2025-09-23 15:19:57
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Exploring the surface chemistry of cesium lead halide perovskite nanocrystals
摘要： Colloidal nanocrystals (NCs) of cesium lead halide perovskites (CsPbX3, X = Cl, Br or I) are emerging as an exciting class of optoelectronic materials, but the retention of their colloidal and structural integrity during isolation, purification and handling still represents a critical issue. The impelling questions concerning their intrinsic chemical instability are connected to the dynamic nature of the bonding between the inorganic surface and the long-chain capping ligands. However, the key aspects of CsPbX3's surface chemistry that directly impact their stability remain elusive. In this contribution, we provide an in-depth investigation of the surface properties of differently composed CsPbX3 NCs, prepared by traditional hot-injection methods. The study, mainly relying on solution NMR spectroscopy, is backed up by elemental analysis as well as morphological, structural and optical investigations. We ascertained that the nature of the ligand adsorption/desorption processes at the NC surface is dependent on its elemental composition, thus explaining the origin of the instability afflicting CsPbI3 NCs. We also evaluated the effect of NC purification as well as of the degradation pathways involving the organic shell on the surface chemistry of CsPbX3 NCs. This study paves the way for new post-functionalization strategies for this promising class of nanomaterials.
关键词： surface chemistry,colloidal stability,degradation pathways,cesium lead halide perovskite nanocrystals,purification,ligand adsorption/desorption,NMR spectroscopy
更新于2025-09-19 17:15:36